The present invention relates to a control system for an automatic vending machine, which is capable of rewriting a control program for controlling a terminal control unit such as a display device.
In control of an automatic vending machine in general, sections of the automatic vending machine are divided into a plurality of blocks, and the thus divided blocks are controlled by means of terminal control units, respectively, which are in turn integratedly controlled by a main control unit. In such an automatic vending machine, it is sometimes demanded that the terminal control unit has its control program changed because of partial change of the specification of the vending machine after installing thereof. Description will be made of a change in display device, by way of example, which is one of the terminal control units.
FIG. 4 is a block diagram showing the arrangement of a conventional display device. The display device 2 is connected to a main control unit through a signal line 6, and an amount indicator, an out-of-change state indicator, etc. of the automatic vending machine are controlled, by way of a CPU 2a. A control program of the CPU 2a is written in a PROM 2g, and various data required for controlling the terminal control units are stored in a RAM 2c. 
Some of the display devices 2 having such the arrangement have been so developed that they display not only the amount of a commodity and the out-of-change state but also advertisements and various kinds of messages. In such a display device of the automatic vending machine, when the displaying manner or the displayed message is changed after installing thereof, the PROM 2g is required to change its contents. In such a case, in the conventional display devices, new PROM""s in which new programs and data are written are newly provided corresponding in number to the number of the objective automatic vending machines. Further, a person in charge makes the rounds of the installed automatic vending machines, to thereby replace the old PROM""s by the new ones.
In such a manner, however, the new PROM""s must be prepared corresponding in number to the number of the CPU""s which are subjected to program updating. In addition, if the person in charge of mounting the PROM""s does not have some experience in the replacing task, he can unfortunately bend a terminal pin of an IC. As a result, the conventional method can impose a problem of a heavy cost.
On the other hand, a ROM, for storing therein a program may be formed by a ROM which can rewrite its data, such as a flash ROM, whereby the program can be updated without exchanging the ROM. However, when the program updating operation is carried out in the display device 2, for instance, the display device 2 cannot respond to a query signal output from the main control unit. Therefore, the main control unit executes a process for determining communication abnormality, to thereby stop its subsequent communication to the display device 2. As a result, after completion of the program updating operation of the display device 2, communication to the main control unit 1 cannot be performed, and therefore the power source of the automatic vending machine has to be once cut off and reset. This can cause a significantly cumbersome task.
The present invention is proposed to eliminate the above-mentioned problems, to thereby readily carry out updating of the control program of the terminal control unit.
To solve the aforesaid problems, a first object of the present invention is to provide a control system for an automatic vending machine, including a plurality of terminal control units and a main control unit for integratedly controlling the terminal control units, wherein a memory device which can electrically rewrite data stored therein is allowed to store a control program in each of the terminal control units, wherein the each of the terminal control units executes by itself updating of the control program stored in the memory device, wherein the each of the terminal control units notifies the main control unit of starting of an updating operation thereof, prior to starting of the updating operation, and wherein the main control unit does not execute an communication abnormality determining process even if the main control unit does not receive a communication signal from the terminal control unit. As a result, the program can be updated without exchanging a ROM, and further the main control unit does not execute an communication abnormality determining process during execution of the program updating operation at the terminal control unit.
Further, a second object of the present invention is to provide the control system for the automatic vending machine, wherein the each of the terminal control units has a card connector provided therefor, the each of the terminal control units functioning, upon insertion of a memory card storing a control program for updating into the card connector, to transcribe the control program for updating from the memory card into the memory device. As a result, the program updating operation can be carried out only by inserting the memory card.